All-in-one panels versus PACs: Which is right for your application?

All-in-one automation panels can offer deterministic, real-time control as traditional programmable controllers for many applications, especially for low- to mid-range applications that require a dedicated operator interface (OI). Advantages include simpler architecture, easy remote connectivity options, and lower total cost of ownership for easier industrial Internet productivity.

11/11/2015


Today companies seek control architectures that help them design better machines and plants, operate them smarter, and redefine the interaction with equipment. They are also looking to understand the Industrial Internet and how it can improve production processes and revenue streams.

A traditional original equipment manufacturer (OEM) machine uses a programmable automation controller (PAC) with distributed input/output (I/O) capabilities, a touchscreen operator interface (OI) with data logging, and an industrial security router to enable remote maintenance. The PAC, OI, and router each have their own processor, installation requirements, and software configuration.

While this traditional distributed architecture is necessary for complex, redundant applications, advancements in computing power have now made it possible to combine these functions into one powerful device for OI and control. An all-in-one automation panel not only streamlines the system and simplifies system development, communication, and maintenance, but it also facilitates Industrial Internet connectivity. One point of connectivity allows OEMs to perform remote diagnostics and configuration that reduce bottom-line support costs and improve overall production-line uptime.

The latest all-in-one operator panels include IEC 61131 programming languages (Ladder, Structured Text, Function Block Diagram, Sequential Function Chart, and Instruction List) and built-in secure connectivity for remote access. Think of these as PACs with a built-in OI, rather than just an OI that performs control. Having such a unit can provide tremendous benefits for small machine OEMs.

Given these advancements in control technology, how do you decide whether an all-in-one automation panel or PAC is the best choice for an application? 

Automation panels' advantages

Cost savings: All-in-one automation panels reduce hardware costs. Combining the controller, OI, and secure remote connectivity in one unit means fewer devices to purchase, install, and configure. This saves money on production time and panel space.

Automation panels can significantly reduce software development costs. Many automation suppliers tout the benefits of a shared database between the PAC and the OI panel. When these are separate devices, they still have separate databases at runtime. This means that each new variable must be downloaded to each device. If the controller and OI get out of sync, communication errors and unexpected operation can result.

On the other hand, an all-in-one automation panel offers one database, one development environment, and one library for reusable objects, thereby reducing development costs.

Simplified maintenance: Maintaining one device is less work than maintaining three, especially when the automation system is shipped to an end user hundreds or thousands of miles away. Just cutting the number of spares is a huge maintenance cost savings.

With an all-in-one automation panel, the OI and logic program can be backed up onto a memory card or USB stick. If the end user has separate files for the OI and controller and needs to restore one or both programs, loading different revisions can result in a nonworking system. Having one program to restore is easier and eliminates version compatibility issues.

One device also means a single point of access; no need to connect to multiple ports to monitor or upgrade the system. This can be even more valuable when dealing with remote connectivity, especially if the PAC only has serial port programming. By using an all-in-one automation panel with built-in secure connectivity, OEMs can connect to remote sites by logging into one server. Even in the application where separate PACs or programmable logic controllers (PLCs) are required, an automation panel can act not only as an OI, but also as an industrial router providing a secure path to remotely access the PLCs or PACs for firmware upgrades and maintenance.

There is a valid concern that if the touchscreen or display gets damaged or fails, the control application also fails. Fortunately with today's advanced technology, this is simply not the case. The components used in the all-in-one automation panel are industrial grade-similar to what is used in PACs, and with comparable MTBFs. Even if the screen gets damaged, the CPU and IO communication still remains functional, and the control application can continue to run. If the screen fails, it is still possible to access the panel remotely.

Improved OI performance: It sounds counterintuitive, but combining the PAC and OI into one device can improve the update times for the OI in many applications. This is because the main CPU task for a traditional OI is communications with the controller. When today's operators press a button on the OI screen, they expect an immediate response for the equipment and immediate feedback on the graphic screen. The biggest reason for delays in that response is the need for a communication driver translating between the OI panel and the PAC.

With an all-in-one automation panel, this communication is much faster because it is internal to the same device. There is no need to rely on serial or Ethernet communication links for updating operator screens.

It is important to note that this advantage may be overshadowed by the overall performance requirements. For example, if the control system requirements are consuming the vast majority of the CPU time, then the OI performance can suffer because it runs at a lower priority than the control.

Intuitive user experience: Most panels on the market today use a resistive touchscreen that require customized navigation menus for moving between screens. The latest all-in-one automation panels have the same capacitive touchscreen technology and user experience as today's personal devices, such as phones and tablets. This greatly reduces development and support costs for OEMs, since they don't have to create custom navigation menus. This also means less end user training is required on how to use the interface. 

Use a separate controller when...

Despite the advantages of all-in-one automation panels, there are distinct, compelling arguments for using separate programmable controllers.

System performance: Many control applications, especially for big complicated machines, have performance requirements that cannot be met by one processor on an automation panel. An all-in-one automation panel with a 1GHz CPU and up to 1G RAM can perform as well or better than many low- to mid-range PLCs, even while handling the OI requirements.

Clearly, a PAC controller will outperform an automation panel with a 1GHz CPU in terms of logic scan rate. If an application needs logic scans in the 10 mS range, this can be a delicate balancing act for an automation panel to meet this need while allowing adequate CPU resources for the OI functions. Larger systems may exceed the needs of the single CPU due to specific requirements for logic performance, graphics, data logging, and other tasks. In these applications, a separate PAC controller is the obvious choice.

High availability systems: High availability systems typically need to run 24/7 without interruption. These systems usually require hot-standby, redundant CPUs with synchronized scans to avoid a system shutdown if one component fails. For these kinds of critical infrastructure applications, having a PAC controller with high availability providing zero unplanned downtime is preferable to an all-in-one operator panel. 

Vibhoosh Gupta is product management leader, GE Intelligent Platforms. Courtesy: GEWhich and when

All-in-one automation panels offer the same deterministic real-time control as traditional programmable controllers for a broad range of applications. Programmable controllers are a better fit for applications where extremely fast scan times, very large IO counts, or high performance redundancy are critical. But for low- to mid-range applications that require a dedicated OI, all-in-one automation panels provide a simplified architecture with easy remote connectivity options and lower total cost of ownership, thereby enabling the Industrial Internet age for new levels of productivity, insight, and user experience.

- Vibhoosh Gupta is product management leader, GE Intelligent Platforms. Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering, mhoske@cfemedia.com.

Key concepts

  • For some applications all-in-one control panels can perform as well as and offer advantages over other options.
  • Benefits include easier configuration and better OI performance.
  • Use a separate controller when very fast scan times, large IO counts, or redundancies are critical.

Consider this

Integrated devices may save time to startup and provide better performance in some applications.



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